Investigation of neutrino properties in the processe+e−→νν¯γ

Assuming a nonvanishing neutrino magnetic moment $\mu$ we study $\tau$-neutrino properties in the process $e^{+}{e}^{-}\to \nu \overline{\nu }\gamma$ from the single photon searches at colliders. We find that for a sufficiently large value of neutrino mass, i.e., $m>\mathrm{}2.1\mathrm{}\times \left(\frac{{10}^{10}\mu }{{\mu }_B}\right)$ MeV (where ${\mu }_B=\frac{e}{2m_e}$ is the Bohr magneton), the interference between the diagrams with $Z^0$ and $\gamma$ exchange becomes important and should be taken into account in future $e^{+}{e}^{-}$ experiments. Some cosmological and astrophysical implications of this new heavy-neutrino scenario are briefly discussed.